The energy spent by martial artists can now be analyzed with the help of devices resembling gas masks combined with mini-jetpacks, researchers say.

These findings could help martial artists train to become better fighters, scientists added.

Martial arts such as karate, judo and tae kwon do have been popular for years, and mixed martial arts that combine different techniques have been rising in popularity recently. Investigating what the body is doing in a fight could help shed light on what training martial artists might want in order to perform better.

Scientists have long been able to study only predictable sports that are easy to replicate under lab conditions, such as cycling, where people essentially stay in one place. Now advances in technology are helping researchers to better study complex and unpredictable sports such as judo.

Every sport makes demands on three energy systems: Aerobic metabolism uses oxygen to convert nutrients into energy ; when intense bursts of energy are needed, lactic anaerobic metabolism generates energy without oxygen, exclusively from sugars such as glucose, with lactate as a byproduct; and for very short bursts of energy, alactic anaerobic metabolism produces energy without oxygen and without producing lactate. Aerobic sports include long-distance running, anaerobic sports include weight lifting.

To figure out the relative contributions of each energy system in judo, scientists had judo practitioners, or judoka, wear portable gas analyzers that look a bit like gas masks as well as mini-jetpacks. This helped measure how much oxygen the judoka consumed while exercising. The scientists also looked at how much oxygen they consumed before and after exercise, and blood lactate concentrations before and after exercise. [ See video of judo experiment ]

In one experiment, the judoka performed three different kinds of throws for five minutes, one every 15 seconds. The researchers found some throws demanded higher aerobic activity, such as seoi-nage, or shoulder throws, while others strongly depended on anaerobic activity, such as harai-goshi, or sweeping hip throws. These findings help reveal what exercises martial artists might want to focus on to help in their training.

"Knowing the physiological demands of different exercises and techniques commonly used in judo can improve the way training is directed to the athlete," researcher Emerson Franchini, a sports scientist at the University of Sao Paolo in Brazil, told LiveScience. "We are also focused on recovery processes between matches — in combat sports, normally athletes perform many matches in the same day, and the recovery between two successive matches can be quite important for performance."

The scientists detailed their research online March 20 in the Journal of Visualized Experiments.

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